[TenTec] an antenna question

[Carl Moreschi]

George,

You could not of said it any clearer.  That's exactly my experience also
with radials.

I have a very unique vertical that I use on 80, 75, 40, and 30 meters.  It
is a 60 foot vertical wire running from the ground to the top of a tree.  I
have 16 50 foot radials in the ground.  I have a relay switched matching
circuit at the base that tunes the antenna at 3.5, 3.8, 7, and 10.1 mhz
depending on which relay is activated.  This gives me a very good 1/4 wave
vertical on 80, 1/2 wave vertical on 40, and 5/8 wave vertical on 30.  It is
a great DX antenna.

Carl Moreschi N4PY
Franklinton, North Carolina
n4py at earthlink.net
----- Original Message -----
From: "George, W5YR" <w5yr at att.net>
To: <tentec at contesting.com>
Sent: Thursday, April 03, 2003 2:56 AM
Subject: Re: [TenTec] an antenna question


> Let's keep in mind that radials in physical contact with the earth are
> essentially non-resonant; their length is of importance only to the extent
> that collectively they form an effective ground screen to collect return
or
> displacement current to the feedline inner braid. Their action is not to
> serve as a reflector of sorts to provide some for the waves to "bounce
> against" in the process of being launched. That occurs many wavelengths
away
> in the confluence of the Fresnel and far-field zones and defines the
takeoff
> angle involved in the vertical radiation pattern.
>
> I use eighteen 25 ft radials with a Butternut HF-9V simply because (a)
that
> is about the height of the antenna and (b) I made a good buy on 450 feet
of
> insulated #12 green wire at Lowe's which translates into 18 twenty-five
foot
> radials. The wire size is massive overkill, but it was cheap!
>
> Jerry Sevick demonstrated in the 70's that 0.2 wavelength radials are
> essentially as effective as anything longer and a rule of thumb that
radials
> as long as the vertical is high works out pretty well.
>
> Elevated radials are an altogether different story. There you want (a)
> resonance and (b) a balanced configuration so that the radiation among the
> radials is cancelled as much as possible. So symmetry is important.
> Preferably one would tune a pair or two of radials for each band in use.
>
> However, ground-mounted radials are largely frequency independent and the
> aim there is just to get as much copper in the immediate vicinity of the
> feedpoint as is feasible. More shorter radials are preferable to fewer
> longer radials, according to Jerry's extensive experiments. All this is
> documented in his book on "ununs" and "baluns." As well as in his original
> series in QST.
>
> 73/72, George
> Amateur Radio W5YR -  the Yellow Rose of Texas
> Fairview, TX 30 mi NE of Dallas in Collin county EM13QE
> "In the 57th year and it just keeps getting better!"
> <mailto:w5yr at att.net>
>
>
>
>
>
> ----- Original Message -----
> From: "Stuart Rohre" <rohre at arlut.utexas.edu>
> To: <tentec at contesting.com>
> Sent: Wednesday, April 02, 2003 3:56 PM
> Subject: Re: [TenTec] an antenna question
>
>
> > Yes, the transmatch should handle that OK.
> > The radials are for a lower band and will function as a ground screen
does
> > to an extent on higher bands.
> > 73,
> > Stuart K5KVH
> >
> >
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